1. Field of the Invention
The present invention relates generally to an active suspension system for automotive vehicle which actively controls vehicular driving behaviour for achieving vehicle driving stability and riding comfort. More specifically, the invention relates to an active suspension system which can adjust distribution of reverse rolling moment at front and rear wheels and whereby adjust steering characteristics for enhanced cornering stability of the vehicle.
2. Description of the Background Art
European Patent First Publications Nos. 02 83 004, 02 85 153 and 02 84 053, which respectively correspond to the co-pending U.S. patent applications Ser. Nos. 169,201, filed on Mar. 16, 1988, 176,246 filed on Mar. 31, 1988 and 172,419 filed on Mar. 24, 1988, all of which have been assigned to the common owner of the present invention, discloses active suspension systems with capability of anti-rolling control. Such active suspension control systems monitors lateral acceleration exerted on the vehicle body for predicting or detecting vehicular rolling magnitude for performing anti-rolling control. The disclosed system performs anti-rolling control is performed by controlling hydraulic cylinders in order to cause vehicular rolling in a direction opposite to the vehicular rolling in response to the lateral acceleration. Such actively induced rolling in a direction opposite to vehicular rolling direction will be hereafter referred to as "reverse rolling". Reverse rolling is induced by applying control signals derived by amplifying the lateral acceleration indicative signal value with a predetermined gains which are provided to be opposite polarities between the suspensions oriented at transversely opposite side of the vehicular body.
Such active suspension system is successful in providing both of driving stability and riding comfort as well as higher stability in cornering at normal condition. However, in certain vehicular driving condition, such as emergency steering at or over critical steering speed which may leads lateral slippage of the vehicle, the prior proposed active suspension systems are not complete and leaves a room for improvement.